The Paul Novak murder trial is underway in Sullivan County Court, and it's shaping up as a particularly strange and grim case.

Catherine Novak's body was found Dec. 13, 2008, in the burned wreckage of the family home in the hamlet of Lava.

Prosecutors say her estranged husband, Paul Novak, tried to knock her out with chloroform and then strangled her, and set the house ablaze to conceal his crime.

The trial sets Sullivan County District Attorney Jim Farrell against high-profile defense lawyer Gary Greenwald. Farrell has also brought on his former boss, Steve Lungen, as a special prosecutor.

The burden of proof will be steep. Catherine Novak's death and the fire were originally ruled accidental in the absence of any solid evidence to the contrary. That changed in the spring of 2012, when Paul Novak's ex-girlfriend, the woman for whom he'd left Catherine, came forward.

Michelle LaFrance, who met Paul Novak as a paramedic trainee, began telling that story to the jury on Tuesday. She's been granted immunity.

LaFrance's tale is sordid: her lover mixing chloroform in the attic of their rented home in Glen Cove while she watched and Novak's young kids slumbered under the influence of Benadryl. She told Farrell she knew Novak's plan, and allowed herself to believe he was saving the kids. After the killing, she testified, Novak became more manipulative and controlling, even browbeating her into swinger-style sex with people he'd met online after the couple moved to Florida.

She got involved with another man a year and a half later, and Novak kicked her out, she said. By 2012, she was dating a sheriff's deputy in Florida. The deputy convinced her to talk to police.

Murder is a heavy load for any witness, not to mention one who may shock the jury's sensibilities. LaFrance will be bolstered by Scott Sherwood, the fellow EMT who prosecutors say drove Novak from Long Island to Lava on the night of the fire, but who has his own psychological baggage. Sherwood pleaded guilty to conspiracy in the case.

Greenwald is sure to attack both witnesses on cross-examination; in his opening, he painted them as unstable and untruthful. He'll attack the very notion that the death was a homicide.

Farrell and Lungen will need their police and fire witnesses to explain how a fire once ruled accidental was reopened and relabeled as a homicide, and what evidence changed their minds. They'll need LaFrance and Sherwood to stand up under what will surely be a withering cross-examination by Greenwald.

Greenwald may go after parts of LaFrance's 2012 video statement to police, which Farrell began playing on Tuesday. LaFrance's emotions are all over the place in the video; as she answers police questions about Novak and the plot, she also seems to grapple with how she ended up involved in a murder plot. "I'm completely culpable in this," she told the investigators.